Structural adhesives have been conventionally used for structural bonding in the manufacturing of structural parts that demand stringent mechanical requirements such automobile and aircraft body parts. Generally, heat-curable epoxy adhesives are used as structural adhesives. Such heat-curable epoxy adhesives often require relatively high-temperature curing, e.g. 120-180° C. (248-356° F.). High-temperature curing often requires large autoclaves, higher production run time and may cause exothermic concerns. On the other hand, there are conventional adhesives that are curable at lower temperature, e.g. ambient temperature; however, they lack the toughness and bonding strength properties required for structural bonding in the manufacturing of aerospace structural parts. The structural adhesives for aerospace application must have the durability to withstand the harsh environmental conditions.
For structural bonding operations such as rapid assembly of aircraft parts, it is desirable to have an adhesive that enables low temperature or room-temperature curing flexibility, out-of-autoclave (OOA) processing, and is capable of forming strong bond to both composite and metal surfaces with excellent long-term durability under aerospace environmental conditions.